spi: dt-bindings: nuvoton,npcm-pspi: Convert to DT schema

Convert the Nuvoton NPCM PSPI binding to DT schema format.

Also update the binding to fix shortcoming:
 * Drop clock-frequency property: it is never read in the NPCM PSPI
   driver and has no effect.

Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20251112150950.1680154-1-tmaimon77@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: tmaimon

Documentation/devicetree/bindings/spi/nuvoton,npcm-pspi.txt

@@ -0,0 +1,72 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/nuvoton,npcm-pspi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton NPCM Peripheral SPI (PSPI) Controller
+
+maintainers:
+  - Tomer Maimon <tmaimon77@gmail.com>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+description:
+  Nuvoton NPCM Peripheral Serial Peripheral Interface (PSPI) controller.
+  Nuvoton NPCM7xx SOC supports two PSPI channels.
+  Nuvoton NPCM8xx SOC support one PSPI channel.
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,npcm750-pspi # Poleg NPCM7XX
+      - nuvoton,npcm845-pspi # Arbel NPCM8XX
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description: PSPI reference clock.
+
+  clock-names:
+    items:
+      - const: clk_apb5
+
+  resets:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+  - resets
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,npcm7xx-clock.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/reset/nuvoton,npcm7xx-reset.h>
+    #include "dt-bindings/gpio/gpio.h"
+    spi0: spi@f0200000 {
+        compatible = "nuvoton,npcm750-pspi";
+        reg = <0xf0200000 0x1000>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pspi1_pins>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clk NPCM7XX_CLK_APB5>;
+        clock-names = "clk_apb5";
+        resets = <&rstc NPCM7XX_RESET_IPSRST2 NPCM7XX_RESET_PSPI1>;
+        cs-gpios = <&gpio6 11 GPIO_ACTIVE_LOW>;
+    };
+